The present invention relates to silage or grain storage buildings, and more specifically to novel door structures adapted for use with automatic silage or grain unloading equipment, and improved positioning means for said unloading equipment.
Silo unloader systems are well known, and one particular system which has proved extremely successful in practice, and to which the improved positioning means this invention relates, is disclosed in U.S. Pat. No. 3,698,575, issued to R. F. Koser and J. D. Messiner, Oct. 17, 1972. Briefly, the system as disclosed in this patent, provides an unloader which rests atop the surface of the silage, and rotates to bring an auger type conveyor into engagement with the silage wherein the silage is conveyed to an impeller; from the impeller the silage is delivered to the discharge chute and expelled through openings in the silo wall, provided by a vertically extending door structure. As the silage is removed, the unloader will move downwardly in response to the decrease in the level of said silage. The auger and the impeller rotate about a vertical axis, which rotation tends to produce rotation of the discharge spout or chute which must be maintained in position in alignment with the discharge opening.
To achieve the above-discussed alignment of the discharge chute with the silo wall openings, the aforementioned U.S. patent disclosed specific positioning means. This positioning means, however, requires a specially constructed silo door structure in the wall of the silo, which structure, disclosed to some degree in the aforementioned patent, is disclosed in detail in U.S. Pat. No. 3,605,342, issued to Robert F. Koser, Sept. 20, 1971. More specifically, with the unloader positioning means as employed in the aforementioned patent, it is necessary that the silo door structure provide continuous uninterrupted, parallel inner edges which confine and engage the positioning arm as it moves downwardly from one opening to the next, said engagement being necessary to prevent undesired rotation during movement of the arm.
The requirement for specially designed discharged opening or door structure, has proved to be somewhat disadvantageous, as the above-mentioned system is not fully compatible with older, more prevalent silo constructions. This problem is overcome by the present invention, in that there is provided not only an improved silo door construction adaptable to older silos, but one that can be employed with an unloader system, with the mere addition of an improved positioning means, as will be explained.
Basically, the improved door construction enables a silo to be modified and provided with a substantially continuous inner door frame that corresponds to the curvature of the silo wall, while providing a plurality of aligned, closable discharge openings of proper size for use with unloader structures of the general type as shown in the above-mentioned patent. In this regard, the improved silo door construction of the present invention does not require installation at the time the silo is erected, although it can be employed in this manner, but rather can be used with existing silos of the stave or panel type to adapt each structure for use with automatic unloading apparatus. At this point, it should be noted that while the door system illustrated in the drawings, and to be described hereinafter, was designed primarily for use with automatic unloading equipment, its use is not so limited. In point of fact, initial testing and development work has shown that the present door system is advantageous even when automatic unloading is not contemplated.
With regard to the new improved positioning means for an unloader discharge chute, this is required due to the fact that the general design of the interior door frame is such that it merges smoothly with the inner wall of the silo. As was discussed above, the positioning means as taught by the prior art U.S. Pat. No. 3,698,575 required a special silo door frame structure. The frame structure included cross pieces upon which the positioning arm rested, and which cross pieces cooperated with vertical frame members to define a series of vertically aligned openings. The cross pieces were spaced inwardly of the parallel inner edges of the frame member, such that there was provided a substantially continuous, uninterrupted inner edges along the entire vertical length of the door frame. Accordingly, as the positioning arm moves from one cross piece to the next, incident to downward movement of the unloader, the arm is held confined by the continuous inner edges, and hopefully unwanted rotation of the discharge chute is prevented. The present invention provides novel unloading chute positioning apparatus which is not dependent upon the existence of said continuous inner edges to achieve alignment of the chute during movement of the positioning arm from one level to the next, as will be apparent from the description to follow.
As an additional factor, the positioning means of the present invention may be employed with the unloader and door frame structure as taught by the prior art. In this regard, the reliability and dependability of the overall system is improved, as the present invention insures against any likelihood that the positioning arm may become disengaged from the frame structure, during movement of the positioning arm.